This invention, relates to the provisions of a lubrication free tenter chain and tenter. Elimination of lubrication to the chain pins and rollers of a tenter chain and to the tenter jaw pivot will greatly reduce the quantity of oil required to be put onto the tenter chain or jaw pivot, thereby greatly reducing the chance of oil being thrown off or splattered onto the cloth. A self-lubricating bushing liner or bushing can be used in place of oil lubrication, but it must be able to withstand temperatures of up to 450.degree. F. with very high pressure loading caused by the chain tension and have a low wear rate. At present a Teflon-type of material has been used successfully in certain low tension types of tenter chains but these wear excessively in standard types of tenter chains where tension is higher. Metallic bushings have been used in tenter jaw pivots to extend the useful life of the tenter, but these metal bushings require oil lubrication.
Accordingly, it is an important object of this invention to provide a tenter chain having a bushing liner constructed of low friction wear resistant plastic material stable at high ambient temperatures which will be of minimal thickness so that compression thereof does not result in excessive stretching of the tenter chain when under such tension as occurs during normal operation.
Another important object of the invention is the provision of wear strips constructed of Vespel and the like which may be suitably mounted so as to confine the material in case of breakage and to avoid shattering of the material. Vespel is a registered trademark of the E.I. Dupont de Nemours Company used to describe parts which are made from Dupont's polyimide resin.
Still another important object of the invention is the provision of a dovetail mounting and/or the employment of countersunk rivets so as to provide a lubrication free tenter chain while avoiding contamination with provision for thermal expansion of the wear strips and the like.
It is also an important object of the invention to provide a self-lubricating bushing for the tenter clip jaw pivot.